WIP - Fix/cucumber2 requires

[olleolleolle]

This is me trying to fix #36 - support Cucumber 2.0.

TODO:

• take care of cannot load such file -- cucumber/ast/scenario #41
• make it recognize the background.
• make it print the names of the scenarios
• pass all scenarios

Failing Scenarios:
cucumber features/feature_pages.feature:6
cucumber features/feature_pages.feature:38
cucumber features/feature_pages.feature:43
cucumber features/feature_pages.feature:48
cucumber features/feature_pages.feature:57
cucumber features/feature_pages.feature:65
cucumber features/feature_pages.feature:70
cucumber features/feature_pages.feature:86
cucumber features/feature_pages.feature:90
cucumber features/feature_pages.feature:97
cucumber features/feature_pages.feature:102
cucumber features/pretty_face_report.feature:10
cucumber features/pretty_face_report.feature:17
cucumber features/pretty_face_report.feature:23
cucumber features/pretty_face_report.feature:27
cucumber features/pretty_face_report.feature:38
cucumber features/pretty_face_report.feature:42
cucumber features/pretty_face_report.feature:49
cucumber features/pretty_face_report.feature:52
cucumber features/pretty_face_report.feature:55
cucumber features/pretty_face_report.feature:64
cucumber features/pretty_face_report.feature:68
cucumber features/pretty_face_report.feature:74

Inspiring usages of the new API

cucumber/cucumber-ruby#839